Automatic self-centering pulleys for belt conveyors



E. T. LORIG 2,995,945

AUTOMATIC SELF-CENTERING PULLEYS FOR BELT CONVEYORS Aug. 15, 1961 Original Filed Dec. 23, 1 953 2 Sheets-Sheet 1 INVENTOR.

saw/1v r. LOR/G, $14554 his Attorney.

E. T. LORIG Aug. 15, 1961 AUTOMATIC SELF-CENTERING PULLEYS FOR BELT CONVEYORS 2 Sheets-Sheet 2 Original Filed Dec. 23. 1953 INVENTOR.

EDWIN 7'. LOR/G,

his Attorney.

United. States Patent This invention relates to automatic self-centering pulleys of rolls for belt conveyors and more particularly to pulleys whichcan be used with reversing conveyors. Conventionalbeltconveyors usually include a fabric or rubber belt pa'ssingover crowned drive and tail pulleys.

The loaded belt is supported by troughing idler pulleys spaced ;at intervals between the head and "tail pulleys and the return run of the belt is usually supported on flat idler pulleys." The only elements in this conventional conveyor which-can align the belt are the drive and tail pulleys. any centering ability and if incorrectly adjusted will actually drive the. belt out of alignment. For these reasons it is often diflicult to keep the belt aligned, and with reversing belts it is sometimes almost impossible to make the belt track properly. Instead of stationary idlers belt training devices such as center swivel-mounted idlers are used along the length of the belt. Most devices in general use are for unidirectional belt operation and depend for their operation on pressure or friction on the edge of the belt, this resulting in damage to the belt itself. Swivelling devices require careful maintenance since failure of an idler to swivel will aggravate tracking difiiculties. Since the corrective effects of such devices remain in full force as the belt approaches the center, the belt instead of moving to the center and staying there will hunt. In other words, it will move from side to side of the center line. The present application which is a division of my co-pending application Serial No. 399,897, now Patent No. 2,919,793, filed December 23, 1953, relates primarily to flat idler pulleys.

It is an object of my invention to provide fiat idler pulleys for belt conveyors which will center the belt regardless of direction of travel without damaging the edge of the belt.

Another object is to provide such pulleys which do not include a swivelling element and in which the centering force diminishes as the belt approaches the center.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a schematic elevation of a belt conveyor system to which self-centering idler pulleys have been pp FIGURE 2 is a view, partly in section, taken on the line 1IH of FIGURE 1 and showing the details of an automatic self-centering troughing idler pulley;

FIGURE 3 is a view taken on the line IHIII of FIG- URE 2;.

FIGURE 4 is a view taken on the line IVIV of FIGURE 2;

FIGURE 5 is a view, similar to FIGURE 2, showing a slight modification of the automatic self-centering troughing idler pulleys;

FIGURE 6 is a view taken on the line VI-VI of FIGURE 1 and showing the automatic self-centering return idler pulley of my invention;

FIGURE 7 is a plan view, partly in section, of the roll of FIGURE 6; and

FIGURE 8 is a view taken on the line VIIIVIH of FIGURE 6.

Referring more particularly to the drawings, reference The .troughing and return idlers do not have Patented Aug. 15,1961

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numeral 2 indicates a pair of spaced apart head and/or tail pulleys around which a belt B travels. Pulleys 2 may be cylindrical, crowned or automatic self-centering and the belt may be driven in either direction by means of a motor 3. A plurality of spaced apart. troughed idler pulleys '4 are provided for the top run'of the belt B and a plurality of spaced apart flat idler pulleys 6 are provided for the bottom run of the belt. A load L is supported on the upper run of the belt B. As shown in FIGURES 2 to 4, the rolls 4 consist of-identical substantially frustoconical shells or rollers 8 each supported by the web 9 in bearing 10 and by web 11 in bearing 12. The bearings 10 and 12 are supported on a shaft 14. The axes of the shafts 14 are arranged at 'an angleto the horizontal in a common vertical plane. The shells 8 are shaped so that they touch on the vertical center line of the assembly and form a belt supporting surface of the desired troughed shape. The lower ends of the shafts 14 are threaded into a member 16 having a cylindrical portion 18 which may rotate a slight amount about its horizontal axis h--'h. The axes of the shafts 14 intersect on the horizontal axis hh. The cylindrical portion 18 is supported in a trunnion bearing 20. i The upper end of each shell8 is prevented from moving upwardly by means of a collar 22 which is fastened to the shaft 14 and bears against the upper bearing 10. The upper end of each of the shafts 14 is supported for movement in an arcuate slotted opening 24 in a bracket 26. Gear teeth 27 are preferably arranged on the adjacent ends of shells 8 to provide for positive rotary synchronous movement thereof.

The operation of the device is as follows:

Assuming that the belt is moving from right to left as seen in FIGURE 1, and that the belt hangs in shallow loops between each pair of troughing idlers, each particle of the load L will change its direction of travel 'as it follows the loop. The force required to change the direction of the belt B is provided by the pressure of the pulley against the belt, this pressure being indicated by the arrow P in FIGURE 1. Pressure P has a horizontal component Ph which causes the shafts 14 to rotate about axis h-h in the direction of belt travel to the one end of slots 24. The movement of the ends of the shaft 14 causes a toe-in efiect on the pulley shells 8 which produces a centering eflEect on the loaded belt in the same manner as the rolls disclosed in my prior Patent No. 2,593,157, dated April 15, 1952. As the direction of belt travel is reversed the direction of force P is also reversed and the shafts 14 will rotate about axis hh in the opposite direction and to the opposite end of the slots 24.

In the embodiment of my invention shown in FIGURE 5, the construction and operation is the same except that the shells 8' are cylindrical rather than substantially frustoconical. Thus the belt B will be supported on its ends but not at its center. Those parts in FIGURE 5 corresponding to the parts of FIGURE 2 are indicated by priming the reference numerals as applied in FIGURE 2. This roll is used particularly with metal belts.

The return idler pulley shown in FIGURES 6 to 8 consists of two identical cylindrical shells 30 each supported by the web 31 in bearing 32 and by web 33 in bearing 34. The bearings 32 and 34 are mounted on a shaft 36. A collar 38 at the outer end of each shaft 36 prevents outward movement of the shells 30. Suitable means (not shown) may be provided for causing positive rotary synchronous movement of the shells 30. The shafts 36 are horizontally cantilevered symmetrically about and at right angles to the center line of the conveyor by means of a common support bracket 40 into which the shafts are threaded. The outer or free end of each shaft 36 is supported by a link 42 which in turn is pivotal-1y mounted at its upper end by means of a pin 44 carried by a bracket 46. It will be seen that the shafts 36 can move in a substantially horizontal plane without any substantial movement in a vertical plane. As the belt B passes over the roll '6 in the direction shown in FIGURE 1, the shafts 36 and shells 30 are deflected horizontally at their outer ends in the direction of travel, thus providing a :toe-in effect which causes a belt centering effect similar to that described above in discussing the operation of the roll of FIGURES 2 to 5. The movement of the shafts 36 is permitted by the inherent resiliency present in. all cantilevered shafts or beams. This pulley may also be used on the top run of flat belt conveyors in place of pulleys 4.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may bemade without departing from the scope of the following claims.

I claim: 7

1. An automatic self-centering pulley for belts or the like comprising a pair of opposed rotatable rollers, a separate shaft for each of said rollers, shaft mounting 'means for the adjacent ends of said shafts, said means including amember held from movement in vertical and "horizontal directions and to which the inner ends of the shafts are attached, and mounting means for the outer end of each shaft permitting simultaneous and independent limited longitudinal movement of said outer ends in the direction-of travel of said belt, said mounting means including an upwardly extending link having means on its lower end forsupporting the outer endof its associated shaft and means for supporting the upper end of said link for pivoted movement.

2. An automatic self-centering pulley for belts or the like comprising a pair of opposed rotatable generally cylindrical rollers, a separate shaft for each or said rollers, the axes of said shafts being in substantially the sameshorizontal plane, shaft mounting means for the adjacent ends of said shafts, said means including a member held from movement in vertical and horizontal directions and to which the inner ends of the shafts are attached, and mounting means for the outer end of each shaft permitting simultaneous and independent limited longitudinal movement of said outer ends in the direction-of travel of said belt, said mounting means including an upwardly extending link having means on its lower end for supporting the outer end of its associated shaft and means for supporting the upper end of said link for pivoted movement.

References Cited in the file of this patent UNITED STATES PATENTS 1,022,949 Johnson Apr. 9, 1912 1,344,171 Byron June 22, 1920 1,842,946 Prins Jan. 26, 1932 2,366,390 Dodge Ian. 2, 1945 

